pranayama unsettles my meditation practice

Why are you practicing pranayama? Sounds like if it's disturbing your sleep, you're practicing it too intensely. Like any kind of physical exercise, it's all about how you do it. If you do it gentle and smooth, it should't disturb your sleep. Any kind of physical exercise done too intensely, you can injure yourself, raise your adrenaline, etc, and disturb your sleep pattern.

The advice you received was wrong. Both asana & pranayama can harm & even ruin the natural flow of consciousness & breathing required for Buddhist meditation & dissolution of stored defilements.

The Buddhist practise called “anapanasati” means remembering to let go of craving so the mind becomes quiet & naturally aware of the in & out breathing. Anapanasati is not a form of pranayama. Even most meditation techniques taught by Buddhist commentators & teachers are wrong. When the mind suspends craving & is quiet, the experience of anapanasati will unfold & progress naturally.

Yoga does have both physiological and psychological benefits, when practised lightly and not as an ascetic practice, however, it is not tied to the Buddhist goal of Nirvana. The Buddha also practice certain forms of it and gave up as it was not linked to the goal of Nirvana which The Buddha was searching. At certain extremities, this is counterproductive, for physical well being, psychology and meditation.

As you have said, some forms can be unsettling and not conducive to meditation. This is especially true for mindfulness.

E.g. following is a paragraph which highlights extreme forms of Khecarī mudrā / kriya leads to unsettling which is not conducive to meditation especially mindfulness:

Clenched teeth, tongue pressed against the palate

Aggivessana, it occurred to me, ‘Suppose, with my teeth clenched and my tongue pressed against my palate, I beat down, hold back, and crush the mind with mind.’

So, with my teeth clenched and my tongue pressed against my palate, I beat down, held back, crushed the mind with mind. While I did so, sweat ran from my armpits.

It was just as if a strong man, holding a weaker man by the head or shoulders, were to restrain, subdue, and attack him;

even so, with my teeth clenched and my tongue pressed against my palate, I beat down, held back, and crushed the mind with mind, and sweat ran down my armpits.

But although I exerted tireless energy, and unremitting mindfulness was established in me, my body was overstrained and lacking calm,

because I was exhausted by the painful striving.

But, Aggivessana, such painful feeling that arose in me did not invade my mind and remain.

Mahā Saccaka Sutta

Similarly, extreme Prāṇāyāma and Bandha also leads to unsettling experiences not conducive to meditation especially mindfulness:

Breathingless meditation

(1) Aggivessana, it occurred to me, ‘Suppose I practise the breathingless meditation.’

So I stopped my in-breaths and out-breaths through my mouth and nose. While I did so, there was a loud sound of winds coming out from my ear-holes, just like the loud sound of winds from a smith’s bellows.

But although I exerted tireless energy and unremitting mindfulness was established in me, my body was overstrained and lacking calm, because I was exhausted by the painful striving.

But, Aggivessana, such painful feeling that arose in me did not invade my mind and remain.

Aggivessana, it occurred to me, ‘Suppose I practise further the breathingless meditation.’ So I stopped my in-breaths and out-breaths through my mouth, nose and ears.

ARABLE OF THE STRONG MAN (1)

While I did so, violent winds cut through my head, just as if a strong man were splitting my head open with a sharp sword.

But although I exerted tireless energy and unremitting mindfulness was established in me, my body was overstrained and lacking calm, because I was exhausted by the painful striving.

But, Aggivessana, such painful feeling that arose in me did not invade my mind and remain.

(2) Aggivessana, it occurred to me, ‘Suppose I practise further the breathingless meditation.’ So I stopped my in-breaths and out-breaths through my mouth, nose and ears.

PARABLE OF THE STRONG MAN (2)

While I did so, there were violent pains in my head, just as if a strong man [244] were tightening a strong leather strap around my head as a headband.

But although I exerted tireless energy and unremitting mindfulness was established in me, my body was overstrained and lacking calm, because I was exhausted by the painful striving.

But, Aggivessana, such painful feeling that arose in me did not invade my mind and remain.

(3) Aggivessana, it occurred to me, ‘Suppose I practise further the breathingless meditation.’ So I stopped my in-breaths and out-breaths through my mouth, nose and ears.

PARABLE OF THE BUTCHER

While I did so, violent winds carved up my belly, just as if a skilled butcher or his apprentice were to carve up an ox’s belly with a sharp butcher’s knife.

But although I exerted tireless energy and unremitting mindfulness was established in me, my body was overstrained and lacking calm, because I was exhausted by the painful striving.

But, Aggivessana, such painful feeling that arose in me did not invade my mind and remain.

(4) Aggivessana, it occurred to me, ‘Suppose I practise further the breathingless meditation.’ So I stopped my in-breaths and out-breaths through my mouth, nose and ears.

PARABLE OF THE TWO MEN

While I did so, there was a violent burning in my body, just as if two men were to seize a weaker man by both arms and roast him over a pit of burning coal.

But although I exerted tireless energy and unremitting mindfulness was established in me, my body was overstrained and lacking calm, because I was exhausted by the painful striving.

But, Aggivessana, such painful feeling that arose in me did not invade my mind and remain. Now, Aggivessana, when the devas saw me, some said: ‘The recluse Gotama is dead!’ Other devas said: ‘The recluse Gotama is not dead but dying!’ Still others said: ‘The recluse Gotama is neither dead nor dying: he is an arhat; such is how arhats dwell!’

Mahā Saccaka Sutta

Similar accounts are found in: (Deva) Saṅgarava Sutta, Mahā Saccaka Sutta, Bodhi Rāja,kumāra Sutta, etc. where pitfalls of these practices are discussed.

Yoga practices are fabricating practices creating new Saṅkhāra while the Buddhist practice avoids creating new Saṅkhāra, hence different in the final results.